1. Field of the Invention
The present invention relates to operative units for a plant for continuous development of photographic material, such as film or paper, and in particular for an adaptation of the advancement speed of such photographic material among the different component elements of such a development plant.
2. Brief Description of the Background of the Invention Including Prior Art
A plant for the automatic and continuous photographic development of photographic material like film and paper, comprising substantially a plurality of different, per se known operative units, such as for example photographic film developing machines, labelling machines, printing machines, which can be combined with each other at variable sequences depending on the needs of the different customers, to achieve an automatic and continuous development of such photographic material is disclosed in the U.S. Pat. No. 4,782,354. This plant is in particular provided with one or more photographic material storage units interposed between the one and the other one of the above mentioned operative units. Each material storage unit includes a set of rotating rollers applied on the upper side of the associated units and having stationary rotation axis. Each material storage unit also includes a set of rotating rollers applied on the lower side of such unit and having rotation axis which are either stationary or displaceable with respect to the upper roller axis. As a result, the photographic material is wound around the respective upper and lower rollers and there is caused a continuous advancement of the photographic material from the One operative unit to the other one during the operation of the plant. Therefore, these storage units, in addition to providing the photographic material advancement, allow also the immediate storage of the photographic material at a variable rate onto such upper and lower rollers, thereby compensating the unavoidable changes of the advancement speeds of the photographic material leaving the directly preceding operative units, in order that the photographic material leaving such storage units may arrive with a predetermined advancement speed at the respective subsequent plant operative unit.
Finally, all the operative and storage units of the such formed plant are connected to one or more data processors. The data processors control the carrying out of the relevant predetermined operative sequences of the operative and storage units to provide for the advancement of the photographic material through all the units, so as to obtain the development and printing of the same material.
A photographic material storage unit is known from the U.S. Pat. No. 4,930,672, which is used in connection with the photographic material developing and printing plant taught in the U.S. Pat. No. 4,782,354. The photographic material storage unit of the U.S. Pat. No. 4,930,672 is substantially identical to the storage units of the plant described in U.S. Pat. No. 4,782,354 and is provided with further sets of upper and lower rotating rollers. These latter rollers have rotation axles displaceable with respect to the axles of the upper rollers. Said rollers are situated at the inlet and outlet side of each storage unit to permit the removable connection of each storage unit with the adjacent plant operative-units. This provides for the advancement of the photographic material through all the units in order to obtain the development and printing of the same material. However, the such formed plant has different inconveniences. First of all, each storage unit exhibits considerable overall dimensions and always includes a compensation mechanism of the photographic material forward speeds, comprising the upper and lower rotating rollers. The storage units are incorporated into an actual photographic material storage warehouse. This results in a complicated construction and requires the availability of considerable spaces for the installation of the storage units together with the different plant operative units.
Besides, such storage unit needs always a certain response time, even if of limited duration, for the compensation of the different photographic material feed speeds between the outlet side of the one operative unit disposed directly upstream and downstream in the same storage unit. This is a result of the unavoidable inertia of the compensation mechanism forming said storage unit. In the case in which the storage unit is spaced away relative to an associated operative unit adjacent thereto, this circumstance might involve undesired changes of the sliding path of the photographic material between such adjacent units, resulting in the hazard of distortions and/or possible breaking of such material. Finally, all the operative and storage units of the plant referred to are controlled in an interdependent manner by the central processing computer unit, such that a possible operative failure or defect in any one of these units may involve an undesired operation such as stopping of the entire plant.